What was learned
Hay et al. report that "a period of warmer and drier climate conditions and possibly increased coastal upwelling offshore occurred ca. 1450-1050 calendar years before present," i.e., from about AD 550-950. In addition, noting that "the patterns observed in the diatom record of Effingham Inlet are consistent with regional marine and terrestrial paleoenvironmental records," they go on to report that "coast range glaciers … showed a hiatus from 1500 to 1100 calendar years before present," and that this "period of more productive conditions … was correlative with increased regional primary and marine fish production." Also, their data indicated that concentrations ofSkeletonema costatum , which they say "is limited by low temperatures," were much greater over the AD 550-950 period (which appears to represent the Medieval Warm Period in this part of the world) than inany portion of the following (most recent) millennium.
What it means
The authors’ data, as well as the data of others they cite, indicate the presence of the Medieval Warm Period in both marine and terrestrial settings throughout the general region where they worked, which period appears to have been significantly warmer than the centuries that preceded and followed it. Hence, Hayet al .’s work presents yet another example of the widespread occurrence of the Medieval Warm Period and its superiority to the Current Warm Period in terms of maximum temperatures, i.e., peak temperatures during the Medieval Warm Period in this part of the world were warmer than those of the Current Warm Period.
Reviewed 1 August 2007
Hay, M.B., Dallimore, A., Thomson, R.E., Calvert, S.E. and Pienitz, R. 2007. Siliceous microfossil record of late Holocene oceanography and climate along the west coast ofVancouver Island, British Columbia (Canada). Quaternary Research 67: 33-49.